This invention relates to suspension systems for vehicles. As used herein, the terms “vehicle” and “vehicles” are intended to include but not be limited to passenger cars, sport utility vehicles, pick-up trucks, commercial trucks, buses, vans, recreational vehicles, motor homes, farm equipment, and non-motorized trailers that carry horses, boats, cars and other loads.
Since the advent of vehicles, numerous suspension systems have been devised to improve the ride of the vehicle not only for the comfort of the occupants but also for maintaining the structural integrity and aesthetics of the contents by providing sufficient lift capability, vehicle stability, and improved handling. For example, motorized vehicles in use since the early 1900s have used simple leaf spring rear suspension systems as have certain non-motorized vehicles such as trailers. Indeed, a substantial number of modern vehicles including, but not limited to pick-up trucks, vans, sport utility vehicles, commercial trucks, and trailers continue to use simple leaf spring rear suspension systems. Some vehicles also use coil spring suspensions.
In addition to simple leaf spring or coil spring rear suspension systems, air springs have long been used in various suspension systems in a variety of vehicle types. In known suspension systems employing air springs, the air springs are firmly attached to supporting members of the vehicle at the top and bottom portions of the air springs. These systems typically require very high air pressure which causes the air springs, and hence the ride on an air suspension, to be stiff. While systems employing air springs provide additional advantage for carrying or towing heavy loads, the ride is generally stiffer. Thus, air spring suspension systems provide lift when heavily loaded but at the expense of the comfort of the occupants which may not be justified during operation of the vehicle without heavy loads.
Various aftermarket devices have been developed to provide increased lift capability and stability of a vehicle when carrying heavy loads. Generally, suspension systems strong enough to provide sufficient lift when loaded are always on and make the ride stiffer during unloaded operation. Suspension systems that don't interfere with unloaded operation may not be strong enough to provide sufficient lift when loaded. Additionally, there is often insufficient space in most vehicles for more than one suspension system. While some systems are quite simple and easily added to existing vehicles, others require significant modifications to the standard “original equipment manufacturer” (OEM) product and/or require complicated installation.
Accordingly, it is an object of the present invention to improve the ride and load-carrying capabilities of existing vehicles with an easy-to-install retrofit suspension system that does not interfere with the factory installed suspension system of the vehicle. The same system can also be integrated into new vehicles to improve ride, handling, and load-carrying capabilities. Another object of the invention is to provide an “on demand” and/or “standby” suspension system that a vehicle operator can engage and disengage as required.
The present invention fulfills these needs and provides other related advantages.